The subcellular distribution of acyl CoA: dihydroxyacetone phosphate acyl transferase in guinea pig liver.

Summarv: Upon differential centrifugation, the enzyme acyl CoA:dihydroxyacetone phosphate acyl transferase (EC 2.3.1.42) in guinea pig liver is shown to sediment in a lysosomal-peroxisomal fraction. Comparison of the distribution of the marker enzymes and of DHAP acyl transferase indicates that the acyl transferase is localized in peroxisomes (microbodies). Acyl dihydroxyacetone phosphate (acyl DHAPl) has been shown to be an important intermediate in the biosynthesis of glycerolipids containing ester and ether bonds (1,2). This lipid is formed by a direct acylation of DHAP with a long chain acyl CoA, and this acyl transferase (EC 2.3.1.42) has been shown to be widely distributed in both the mitochondrial and microsomal fractions of different mammalian tissues (2-6). The activity of this enzyme is very high in guinea pig liver, (3) and the acyl transferase has been solubilized and partially purified from this organ (7). During this work the distribution of this acyl transferase in different subcellular fractions of guinea pig liver was rigorously investigated, and it was found that this enzyme was highly enriched in a particulate fraction which contained mainly lysosomes and peroxisomes. These results are presented here. MATERIALS AND METHODS Palmityl CoA, DHAP, G-3-Pl, cytochrome C, and D-glucose-6-phosphate were obtained from Sigma (St. Louis, MO.). Fatty2acid poor bog$ne serum albumin was from Miles Laboratories (Elkhart, Ind.). [ PIDHAP and [ PIG-3-P were prepared by the enzymatig2phosphorylation of dihydroxyacetone and glycerol respectively with [vP]ATP as described previously (3,s). The 0-nitrophenyl glycoside of N-acetyl-S-D glucosamine was a kind gift of Dr. Otto Sellinger.